1. FIELD OF THE INVENTION
The present invention is related to touch screen sensors, and, more particularly, to a touch screen sensor having a wave absorption material positioned around at least a portion of the touch screen.
2. DESCRIPTION OF THE RELATED ART
Touch screen technology is frequently employed in many settings to facilitate communication with computer systems, e.g., automatic teller machines, cash registers, manufacturing equipment, etc. Touch screens may be made from a variety of materials, such as, for example, glass, metal, plastic, etc.
Typically, a touch screen sensor is comprised of a plurality of reflector arrays and two or more piezoelectric transducers attached to the touch screen sensor.
In general, the piezoelectric transducers are used to generate ultrasonic waves that travel within the touch screen sensor along two different axes, e.g., "x" and "y" axes. As the generated wave travels, fractions of the generated wave are deflected across an active area of the sensor by the reflector arrays. Ultimately, the deflected portions of the original wave are returned to, for example, a receiving transducer where they are converted into electrical signals.
An absorber, such as a finger in contact with the touch screen sensor, draws energy from the fractions of the ultrasonic wave that are deflected across the active area of the touch screen sensor. The reduction in energy of the transmitted pulse appears as a dip in a wave train of the pulse. The location of the dip in time is proportional to the position of the absorber, i.e., the finger, in the subject direction, i.e., in the x-direction. This same technique can be used to determine the location of the touch in the y-direction. Through use of this technique, as well as others known to those skilled in the art, the coordinates of the absorber, i.e., the finger, can be determined. Of course, the determined position of the touch corresponds to a computer command or response, such as, "START," "COMPLETE," "ENTER," "OK," etc.
As the ultrasonic waves are sent out, deflected across the active area of the touch screen sensor, and returned to a receiving transducer, a variety of spurious reflections or echoes of all or a portion of the ultrasonic waves may be generated. Examples of such spurious reflections or echoes include, but are not limited to, second pass reflections, array diffraction echo, corner echo, back edge bounce back reflections, etc. Unabated, such reflections or echoes can cause distortion and errors in the signals received by the receiving transducer. For example, some or all of the reflections may act to completely mask the electronic indication of a touch in the active area of the screen.
One technique currently used to attempt to reduce these type of problems involves the use of a silicone gel positioned between the touch screen sensor and a separate back plate that is used to provide mechanical support to the touch screen sensor itself.
The present invention is directed to an improved touch screen sensor that reduces or eliminates some or all of the above-identified problems.